Equity (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Changes in equity
Beginning Balance			$ 3,134,687,000
Issuance of common shares related to the exercise of stock options, dividend reinvestment plan and director compensation			900,000
Issuance of common shares related to exercise of warrants			134,300,000
Issuance of common shares for cash offering			129,900,000
Contributions from non-controlling interests			200,000
Issuance of restricted stock			200,000
Vesting of restricted stock			$ (100,000)
Stock-based compensation expense			2,700,000
Redemption of preferred shares			(180,000,000)
Dividends declared-common shares			(21,700,000)
Dividends declared-preferred shares			(18,300,000)
Distributions to non-controlling interests			(1,300,000)
Comprehensive income:
Net income	(13,269,000)	(121,166,000)	22,110,000	(147,750,000)
Other comprehensive income (loss):
Settlement/change in fair value of interest-rate contracts	(987,000)	4,102,000	(2,772,000)	7,570,000
Foreign currency translation	7,879,000	(4,255,000)	12,855,000	(16,157,000)
Comprehensive income	(6,330,000)	(121,380,000)	32,233,000	(156,491,000)
Ending Balance	3,213,650,000		3,213,650,000
Preferred Shares [Member]
Changes in equity
Beginning Balance			555,000,000
Redemption of preferred shares			(180,000,000)
Other comprehensive income (loss):
Ending Balance	375,000,000		375,000,000
Common Shares [Member]
Changes in equity
Beginning Balance			25,600,000
Issuance of common shares related to exercise of warrants			1,000,000
Issuance of common shares for cash offering			1,000,000
Issuance of restricted stock			100,000
Other comprehensive income (loss):
Ending Balance	27,700,000		27,700,000
Paid-in- Capital [Member]
Changes in equity
Beginning Balance			3,869,000,000
Issuance of common shares related to the exercise of stock options, dividend reinvestment plan and director compensation			700,000
Issuance of common shares related to exercise of warrants			133,300,000
Issuance of common shares for cash offering			128,900,000
Issuance of restricted stock			(2,300,000)
Vesting of restricted stock			$ 1,700,000
Stock-based compensation expense			2,700,000
Redemption of preferred shares			6,400,000
Other comprehensive income (loss):
Ending Balance	4,140,400,000		4,140,400,000
Accumulated Distributions in Excess of Net Income (Loss) [Member]
Changes in equity
Beginning Balance			(1,378,300,000)
Redemption of preferred shares			(6,400,000)
Dividends declared-common shares			(21,700,000)
Dividends declared-preferred shares			(18,300,000)
Comprehensive income:
Net income			21,900,000
Other comprehensive income (loss):
Comprehensive income			21,900,000
Ending Balance	(1,402,800,000)		(1,402,800,000)
Deferred Compensation Obligation [Member]
Changes in equity
Beginning Balance			14,300,000
Issuance of restricted stock			200,000
Vesting of restricted stock			$ (1,900,000)
Other comprehensive income (loss):
Ending Balance	12,600,000		12,600,000
Accumulated Other Comprehensive Income (Loss) [Member]
Changes in equity
Beginning Balance			25,600,000
Other comprehensive income (loss):
Settlement/change in fair value of interest-rate contracts			(2,800,000)
Foreign currency translation			11,600,000
Comprehensive income			8,800,000
Ending Balance	34,400,000		34,400,000
Treasury Stock at Cost [Member]
Changes in equity
Beginning Balance			(14,600,000)
Issuance of common shares related to the exercise of stock options, dividend reinvestment plan and director compensation			200,000
Issuance of restricted stock			2,200,000
Vesting of restricted stock			$ 100,000
Other comprehensive income (loss):
Ending Balance	(12,100,000)		(12,100,000)
Noncontrolling Interests [Member]
Changes in equity
Beginning Balance			38,100,000
Contributions from non-controlling interests			200,000
Distributions to non-controlling interests			(1,300,000)
Comprehensive income:
Net income			200,000
Other comprehensive income (loss):
Foreign currency translation			1,300,000
Comprehensive income			1,500,000
Ending Balance	$ 38,500,000		$ 38,500,000